Generally speaking, I think political philosophers need to engage more with economic ideas. When this does happen, however, the results are often a bit shit. This is because they tend to take an overly crude and formalistic version of economic theory.
Take Rawls as an example. His Veil of Ignorance is supposed to produce hypothetical unanimity when people are not aware of their particular position in life and are therefore uncertain of which rules and institutions will best advance their interests. This vision is one in which only narrowly-defined incentives affect decision-making. This is consistent with the sort of parody of economic theory that economic sociologists, et al create to show how subtle their thinking is, and it is clearly false.
We can’t get any substantial predictions of behaviour while considering only incentives. Preferences also matter. In fact, it is simple nonsense to speak of free-floating incentives without references to the preferences on which they are parasitic. Preferences are not only material, but also ideological: we care about many things.
While it is possible to abstract from a person’s concrete interests and imagine a neutral position, it is nonsense to abstract from a person’s preferences and imagine a neutral ideology. If we were to abstract away all the biases which constitute an individual’s ideological orientation, there would be nothing left.
Rawls abstracts away individual incentives and obtains neutrality on that front, but also plugs in his own ideological preferences when declaring what the neutral social contractarian would prefer. I certainly don’t prefer Rawls’s minimax criterion of policymaking, even after abstracting away my concrete interests, because compared to Rawls I give liberty more weight than economic security.
Trying to argue that reasonable people will agree to a certain set of institutions if they are in a neutral position with respect to their material interests while plugging in your own ideology is stacking the deck.